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Patented May 19, 1896.

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ELEGTRDMAGNETIU DASH POT.

No. 560,216. Patented May 19, 1896.

UNITED STATES PATENT OFFICE.

JOHN D. II-ILDER, OF YONKERS, NEXV YORK, ASSIGNOR TO THE OTIS BROTHERS &COMPANY, OF NE\V YORK, N. Y.

ELECTROMAGNETIC DASH-POT.

SPECIFICATION forming part of Letters Patent No. 560,216, dated May 19,1896. Application filed February 8, 1895. Serial No. 537,716. (Nomodel.)

To ail whom, it may concern.-

Be it known that I, JOHN D. IHLDER, a citizen of the United States,residing at Yonkers, Westchester county, State of New York, haveinvented certain new and useful I mprovements in ElectromagneticDash-Pots,of which the following is a specification.

My invention relates to electric motors, and more particularly to meansfor regulating the starting of said motors; and it has for its object toprovide improved means for this purpose which shall operateautomatically and magnetically to control the electric current passingto the motor in starting; and the invention consists in the variousfeatures of construction and arrangement of parts, having the mode ofoperation substantially as hereinafter more particularly set forth. 7

Referring to the accompanying drawings, Figure 1 is a diagrammaticrepresentation of one embodiment of my invention. Fig. 2 is a similardiagrammatic representation of a modified arrangement of the invention,and Fig. 3 is a detail view showing a modified arrangement of part ofthe apparatus for carryin g out my invention.

It is well known that in starting an electric motor, especially whenused in connection with a constant-potential circuit, it is desirable toadmit the current to the armature of the motor gradually, an d to dothis it has been common to include a certain amount of resistance in thearmature-circuit of the motor, which resistance is gradually reduced orcut out as the speed of the motor increases and the counterelectromotive force of the motor accumulates. A number of devices havebeen suggested to accomplish this general purpose of automaticallyreducing the auxiliary resistance of the armature-circuit of a motor,and it has been suggested to use in connection with such devices amechanical dash-pot to control their operation, and it is one of theobjects of my invention to do away with this mechanical dash-pot andaccomplish the same purposes and objects by electromagnetic devices, anda portion of my invention may be said to consist in an electromagneticdash-pot, which is arranged and connected with the other parts of theapparatus in such a way as to control or regulate the motor. \Vhile suchan apparatus is capable of many and various uses wherever electricmotors, and especially shunt or compound wound electric motors, areused, I have shown my invention in the present instance as adapted to beused in connection with electric elevators, for which purpose it isspecially adapted, and I will explain the principles thereof in thatconnection,without, of course, intending to limit my invention to suchuses.

It is not deemed necessary to show the entire electric-elevatorapparatus, as such is well known and understood by those skilled in theart, and only the parts necessary to a clear understanding of thepresent invention are displayed in the drawings.

Referring more particularly to Fig. 1, (although corresponding parts aresimilarly lettered in other figures,) A represents the usual wheel orpulley around which the hand-rope A passes, which hand-rope, as isusual, is under the control of the operator in the car of the elevator,and this wheel is mechanically or manually operated by the hand-rope orsome equivalent device in order to start and stop the electric motor,which may be connected in any of the usual ways with the elevator-car orwith other machinery which it may drive.

M represents diagrai'nmatically an electric motor, which may be of anydesired type or construction, but is shown in the present 111- stance asbeing a shunt or compound wound motor, in which a portion of the coilsof the field-magnet are included in a constantlyclosed branch circuitbetween the main-line terminals plus and minus. Thus it will be I seenthat the conductor 1 is shown diagrammatically as forming a portion ofthe fieldmagnet coils in a constantly-closed shunt, although of course,if desired, the usual makeand-break switch may be applied to break theshunt whenever the motor is stopped and to close the shunt whenever itis started.

The armature-eircuit of the motor includes a po1echanger orcurrent-reverser 13, which may be of any usual and well-known type, andwhich in the present instance is illustrated as comprisinga plate orcylinder having on its periphery certain portions of conducting materialand non-conducting material arranged in the well-known manner, and thiscurrent-reverser is also shown as-being operated mechanically by aconnecting bar or red B, which in this instance is connected positivelyto the wheel or pulley A and directs the current through the armature inone direction or the other, according as the wheel or pulley A isrotated in one direction or the other. Also included in thearmature-circuit of the motor is an auxiliary resistance device C,composed in the present instance of a number of plates 0 c o c c c cwith intermediate resistance-coils between the contactplates,except atthe extremities, and between plates 0 0. Connected to operate with thisresistance is a lever-arm D, carrying on its extremity a spring-arm orcontact-piece d, adapted to sweep over the various contactplates 0 as itis moved in the manner hereinafter set forth. In Fig. 1 this lever-armis shown as being mounted 011 an axle E, so that it can rotate freelythereon, and mounted on the same axle or shaft E is a gear-wheel F,having a ratchet-wheel F, with which a pawl D 011 the lever-arm engages,so that when the lever-arm D is moved in one direction the wheel 1* andratchet-wheel F will not rotate, but when they are moved in the oppositedirection the pawl D will engage the ratchetwheel F and rotate the wheelF. This wheel F is connected in the present instance through a train ofwheels F F with a metal disk G, which is mounted in such a relation tothe magnet or pole-piece H as to be within the mag netic field thereof,so that the movements of the disk will be influenced or controlled bysuch magnetic field, thus acting as a magnetic brake or dash-pot. Thismagnetic field may be produced in many and various ways, which willreadily suggest themselves to those skilled in the art, and may be usedin accordance with the requirements or wishes of any particular case.Thus, if it is desired to make a uniform magnetic field in which thedisk shall operate, such field may be readily produced by a shuntwindingfrom the field-magnet circuit, as is indicated in dotted lines 2, whilea variable magnetic field may be produced by winding the magnet orpole-piece II in series with the armature-circuit, and consequently thespeed of rotation of the disk G will vary in proportion to the currentpassing through the armature-circuit, and this is generally a moredesirable arrangement, as the less work the motor has to do the quickerwill the leverarm be allowed to cut out the auxiliary resistanee in thearmature-circuit. This winding (indicated in Fig. 1) will be explainedmore fully hereinafter. So far we have assumed that the weight of thelever-arm itself is sufficient to operate it to cut out the resistancegradually; but if this is insufficient a counterweight D may be appliedto the leverarm, and this is preferable, and preferably is madeadjustable, so that by properly ad justing the switch in relation to theother parts of the apparatus the resistance may be cut out of thearmature-circuit in the most satisfactory manner. This lever-arm D ispreferably arranged so that in cutting out the resistance it can moveunder the control of the magnetic brake or dash-pot device; but when themotor is stopped it is generally desirable to out in the resistance tothe armature-circuit quickly and positively, so that accidents may beavoided, and especially if the motor is again started immediately afterbeing stopped the resistance should all be included in thearmature-circuit without fail, and for this purpose there is provided acam I, which in this instance is attached to the shaft of the wheel orpulley A and is operated mechanically therewith, and is so arranged thatthe lever-arm is positively moved upward or in such a direction as tocutin the resistance whenever the pulley A is moved in a position tostop the motor. Various forms and shapes of cams or other equivalentdevices may be used, but that shownin the drawings is simple andeffective, and it will be observed that the lever-arm D is provided witha stop or stud (P, which fits in the cam recess, and when the parts arein their normal position, as shown in the drawings, the lever-arm israised to its upper position, but when the pulley or wheel A is moved ineither direction the cam-slot permits the lever-arm to move downwardwithout being positively controlled by the cam, but when the cam isrestored to its normal position the lever-arm is positively lifted bythe stud d bearing 011 the cam-face, so that the resistance in thearmature-circuit is positively included.

lVhile, as above indicated, the motor may be variously wound and variousarrangements of the contact-pieces of the resistance maybe made, I haveindicated in the drawings an arrangement in which the contact-piece c isinsulated from the others, so that when the brush (Z of the lever-arm Dis on the contactplate a the circuit of the armature is broken, but assoon as it moves onto contact-plate c all the resistances between theadjacent plates are included in the armature-circuit. lhave also shownan arrangement whereby the series field-magnet coils are arranged insections and are included between some two of the variouscontact-plates. As, for instance, connected to contact-plate c is aconductor 3, which extends to the field-magnet coils of motor M andreturns to contact-plate c.

Again, contact-plate c is connected bya conductor l, which in thisinstance leads to the coils h of the electromagnet or polepiece II, andthence includes a portion of the coils of the field-magnet of the motorM, and, returning, is connected to the contact-plate 0 and it will beobserved that when the brush (1 is 011 the contact-plate c all theseries fieldmagnet coils are short-circuited or cut out, as well as thecoils of the electromagnet ll. From the contaet-plate 0 leads aconductor 5, bearing on the pole-changer B,- and from the pole -changerlead the conductors 6 7,

connected to the brushes of the armature of the motor M, and a conductor8 leads from the pole-changer to the main conductor 1, while a conductor9 connects with the 0011- ductor 1 and with the leverarm D which in thisinstance is shown as being of conducting material, although, of course,it may be otherwise made and the conductor 9 be connected directly tothe brush (Z, or otherwise, as most convenient.

In the position in which the parts are shown in Fig. 1 it will beapparent that while the main field-magnet coils of the motor M areenergized the armature-circuit is broken .be tween the brush cl andcontact-plate c, and is shown as also being broken at the pole changerB, which is the preferred arrangement. Assuming now that the pulley A isturned to the right to start the motor, the polechanger will be rotatedso as to connect conductors 5 and 6 and conductors '7 and 8 and directthe current through the armature of the motor in a certain direction,and at the same time the cam I has moved so that the stud d is free tomove in the cam-space, and the lever-arm (weighted or not, as the casemay be) tends to fall to gradually cut out the resistance 0 on thearmature-circuit. As soon as this moves, however, so that the brush dbears on the contact-plate c, the current passes through the variousresistances and conductors connected thereto, energizing the magnet H,and as the pawl D engages the ratchet-wheel F and rotates the wheel Fand its train of gears connecting it to the disk G this disk will berotated in the magnetic field of the magnet H, which field will tend toretard or control the speed of rotation of said disk, thus regulatingthe movements of the lever-arm D, the magnet H and disk G acting as abrake or dash-pot to the movements of the lever-arm.

As before intimated, as the lever-arm moves, cutting out the resistance,the series fieldmagnet coils 3, when connected in the man ner indicated,are cut out, and subsequently the series field-magnet coils a arecutout, and at the same time the coils h of the magnet H are cut out,when the full current is passing through the armature-circuit and themotor is working at its normal speed as a pure shunt-motor, the seriesfield-magnet coils being used, preferably, in starting the motor, so asto more readily overcome the inertia of the motor and its load and toproduce a relatively great torque at the moment of starting the motor.lVhen it is desired to stop the motor, the cam is restored to its normalposition, and the cam-face is such that it engages the stud d andpositively moves the lever-arm to the position indicated, and in doingso the pawlD passes over the ratchetwheel F without moving the wheel For the disk G, connected thereto. This arrangement embodies in one formthe general principles of my invention in a practically-operatingapparatus for many purposes; but it will be observed that by thisconstruction there is nothing to prevent the lever-arm from cutting outall the auxiliary resistance whenever the cam is moved to release saidarm, and this results in increasing the current in the armature to themaximum amount, and, while this is generally desirable, it may happenfor some reason that the motor does not start properly and the internalresistance or counter electromotive force of the motor does not increasein the proper ratio, so that an undesirable excess of current may passthrough the armature-circuit of the motor; and I therefore provide meanswhereby this excessive current may be avoided and the maximum currentpassing through the armaturecoils may be limited to that which the motorcan properly take without danger. One means of accomplishing this resultis shown more particularly in Fig. 2, where most of the parts are thesame and are similarly lettered as in Fig. 1, and need not be againdescribed. In this instance, however, the lever-arm D is shown as formedor connected with a disk or armature of magnetic metal G, which isarranged to move in the magnetic field produced by the magnets H H, asbefore, but which magnets are energized somewhat differently, aswill nowbe explained. In this case the magnets 11 are continuously energized andtheir coils are not cut out of circuit when the lever-arm reaches itslowermost position and the brush dis on the contact-plate 0 but leadingfrom said contact is a conductor 5, which includes the coils of themagnets H, in series with the armature-circuit at all times, as isclearly indicated in the diagram, and this is true whether the seriesfieldmagnet coils 3 4, when used, are in or out of the series circuitand whether the motor is operating as a compound or simple shunt motor.This magnet and the circuits thereof are so arranged and themagnetization produced is such that the disk 01' armature G tends toturn in a direction to cut in the re sistance 0, while the weight Dtends to move the lever-arm D, and consequently the disk or armatureconnected thereto, in an opposite direction. It will readily be seenthat by properly proportioning the strength of the magnetic field andthe disk or armature thereof with relation to the weight such a torquemay be produced on the disk 01' armature G as to just balance the weightof the lever-arm for a predetermined current passing through thearmature and the magnets thereof, so that if an excessive amount ofcurrent passes through the motor M and the magnets H and disk orarmature thereof the lever-arm will be moved upward to include more ofthe resistance until the resistance of the motor is increased to such anextent as to properly admit the entire current to pass through it, andit will thus be seen that I am enabled to so adjust the parts that undernormal conditions the resistance will be gradually and regularly cut outof circuit,

but under abnormal conditions the resistance will be cut in or out,according to the requirements of the case, so that all danger ofinjuring the motor or other parts is avoided, the apparatus beingself-regulating and positive in its operation.

It will be obvious that the leverarm may be attached directly to thedisk or armature G, as shown in Fig. 2, or indirectly, as shown in Fig.3, wherein the lever-arm D is connected to or mounted 011 a separateshaft D and connected by gears to the armature G, or it may be arrangedin any other equivalent manner, it being only necessary that it can bemoved backward to cut in the resistance 0 by the armature or disk G.Furthermore, the revolving disk or armature G may be of any suitableconstructionas, for instance, a thin copper disk when used in the mannershown in Fig. 1, in connection with the magnet or pole-piece II, or aniron disk or drum, as shown in Fig. 2, which may be constructed invarious shapes and proportions and wound with more or lessarmature-coils 10, or it may be of non-magnetic material, or it may besimply a series of coils or any other well-known equivalent structure.Furthermore, it is not absolutely necessary to have the pole-pieces ll,as surrounding the disk or armature with magnetized coils of wire may bemade to answer the purpose; but I have not deemed it necessary to showall these modifications, as they are well-known equivalents of thestructure shown, which is illustrated as typical and not as limiting myinvention to the pre cise construction set forth.

It will further be understood that although the motor is shown as havinga compound winding and the compound series field is divided into severalparts and connected thereto between different resistance contact-platesother well-known arrangements may be provided; but by arranging thecircuits in the manner illustrated the strength of the motorfield isgradually reduced, the speed thereof increasing steadily and withoutfluctuations of. the armature-circuit.

Instead of the adjustable weight on the lever-arm heretofore described Imay use a friction-brake, such as is illustrated in Fig. 3, in whichthere is a brake-piece K secured to the side of the pole-piece or magnetII and having one end bearing on the disk or armature G. Thisbrake-piece is shown as mounted on a stud 7;, having a spring 7a, whichtends to hold it against the face of the pole-piece, and anadjusting-screw k for regulating the air-gap between the brake-piece andthe polepiece. lVith this arrangement it will be seen that thebrake-piece K is pressed against the disk with a pressure that varies asthe magnetism in the pole-piece and disk varies, and this varies withthe eurent, in the manner heretofore pointed out, and the motion of thelever-arm is thereby regulated through the medium of the brake-piece inaccordance with the current flowing through the motor. I

have found it advantageous sometimes to tip the brake-piece K withnon-magnetic material K where it bears upon the disk or armature toprevent the parts sticking together. It will be seen that by regulatingthe air-gap between the magnet and brake-piece the force or power of thebrake can be accurately and delicately adjusted.

A circuit-breaking switch maybe operated to open and close thearmature-circuit or both the armature and field, and in Fig. 1 I haveshown an arm 0, arranged to bemoved with the hand-rope wheel A and tooperate a switch arm P, controlling the terminals P P in a manner wellunderstood. It is evident that the portion 1 of conductor 1 may beomitted and the whole current pass by the conductor 1. through thebreak-switch, thus opening and closing both the armature and fieldcircuits, or the portion S) of conductor 9 may be omitted and thebreak-switch P used to control the Q-IlllttlllG-OllClllt only. All thesedetails of circuit connections, however, do not materially affect myinvention.

Having thus described the general principles of my invention andillustrated the preferred manner of applying the same, so as to enablethose skilled in the art to make use thereof, what I claim is 1. Thecombination with a motor and resistance device in the armature-circuitthere of, of a lever-arm controlling said resistance device, and anarmature connected to said lever-arm and controlling its movements inone direction, said armature moving in a magnetic field controlled bythe resistance device, substantially as described.

2. The combination with a motor and resistance device in thearmature-circuit thereof, of a lever-arm mechanically operated to cutout said resistance from the armatureeircuit, and an electromagneticdevice connected to the arm to control its movement in cutting out theresistance, the said electromagnetic -device comprising an armaturemoving in a magnetic field controlled by the resistance device,substantially as described.

The combination with a motor and resistance device included in thearmature-circuit of the motor, of a lever-arm mechanically operated tocut out said resistance device and mechanically and positively operatedto cut in said resistance device, and an armature connected with saidlever-arm to control its movement in cutting out the resistance, thearmature moving in a magnetic field controlled by the resistance device,substantially as described.

l. The combination with a motor and resistance device therefor, of alever-arm mechanically operated to cut out said resistance, and a diskconnected to said lever-arm, said disk rotating in a magnetic field tocontrol the movements of said lever-arm in one direction, the magneticfield being controlled by the resistance device, substantially asdescribed.

5. The combination with a motor and resistance device included in thearmature-circuit of the motor, of a lever-arm mechanically operated inone direction and controlled by an electromagnetic device and positivelyand mechanically operated in the other direction to cut in theresistance device, substantially as described.

(3. The combination with a motor and resistance device included in thearmature-circuit of the motor, of a shaft, means for moving the shaft, alever-arm controlling the resistance device, connections on the shaftfor positively moving the lever-arm in one direction, a pole-changer inthe armature-circuit connected to be moved from the shaft, and acurrent-breaking switch controlled from said shaft, substantially asdescribed.

7. The combination with a shunt-motor and resistance device included inthe armaturecircuit, of series field-magnet coils connected to saidresistance device at different points thereof, means for controllingsaid resistance device and arranged on starting the motor to include theseries field-magnet coils in the armature-circuit and to cut them out asthe resistance is cut out of the armature-circuit, and electromagneticdevices for controlling said means, substantially as described.

8. The, combination with a sh unt-motor and resistance device includedin the armaturecireuit, of series field-magnet coils connected to theresistance device at different points, a lever-arm for cutting in andout said resistance device and controlling the series fieldmagnet coils,an electromagnetic device controlling said lever-arm in cutting out theresistance and included in the armature-circuit, and mechanical meansfor positively moving said lever-arm to cut in the resistance,substantially as described.

9. The combination with a motor and resistance device in circuittherewith, of aleverarm controlling said resistance, a disk rotating ina magnetic field, and a pawl-and-ratchet connection between said diskand lever-arm, substantially as described.

10. The combination with an electric motor and resistance devicetherefor, of series fieldmagnet coils for the motor connected with saidresistance device, a lever-arm controlling said resistance device, adisk connected with said arm, and a magnet controlling said disk andincluded in the resistance-circuit, substantially as described.

11. The combination with a motor and resistance device in the circuitthereof, of a lever-arm controlling said resistance device, a cam formoving said lever-arm in one direction, a disk controlling the movementsof the lever-arm in the other direction, and a magnet controlling thesaid disk, substantially as described.

12. The combination with a field-magnet and a disk or armature, of abrake-piece connected to said field-magnet and bearing on the disk orarmature and having a piece of non-magnetic material on itsarmature-bean ing face, substantially as described.

13. The combination with a field-magnet and a disk or armature, of abrake-piece connected to said field-magnet, and means for adjusting theair-space between the brakepiece and field-magnet, said brake-piecebearing on the armature and acting as a brake therefor, substantially asdescribed.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

JOHN D. IHLDER.

Witnesses:

JAMES S. FITCH, O. B. WARING.

